The moment came as Newt Gingrich was parrying Mitt Romney’s constant boast that he’s spent most of his career in the private sector. Gingrich noted that Romney had tried and failed to gain a seat in the U.S. Senate by taking on the prominent Democrat.

“The only reason you didn’t become a career politician is you lost to Teddy Kennedy in 1994,” Gingrich said. “…You’d have been a 17-year politician by now if you’d won.”

Romney gave a toothy smile as some in the crowd booed and others clapped. Then he said it was probably true that he would have become a career politician if he’d beaten Kennedy. “And if I would have been able to get in the NFL like I hoped when I was a kid, I’d have been a football star all my life. I spent my life in the private sector. Losing to Teddy Kennedy probably was the best thing I could have done to prepare myself for the job I’m seeking, because it put me back in the private sector.”

Kennedy and Romney cooperated later when Massachusetts was working to pass a health-reform bill while Romney was the state’s governor. Parts of that 2006 bill are similar to what President Obama pushed through Congress last year, which has caused Romney some heartburn now.

Romney was asked repeatedly Saturday about the issue. The most controversial part of the Massachusetts plan was a requirement that nearly everyone have health insurance, and that they buy it if they could afford to. Romney said it’s unconstitutional for the federal government to invoke such a mandate, as Obama’s plan does. But “states can do whatever the heck they want to do. That’s the great thing about our system,” he said.

Romney repeated his vow to rid the country of “Obamacare.” He said the national program should be replaced with state experiments, some of which could resemble the Massachusetts plan. “I think there’s a good deal of what we did that people could look at and find as a model that could help their state if they want to. … It’s up to other states to try what works for them. Some will like that, some will think it’s a terrible idea.” He pointed out that his plan relied on private insurers.

Texas Gov. Rick Perry tried to tie Romney to the Obama plan by noting that a first edition of Romney’s book included a line about how Massachusetts’ health-care plan could be a model for the country. Romney said he never said it should be a model for the federal government. When Perry persisted, Romney stuck out his hand toward the Texan. “Ten thousand-dollar bet?” he said.

Perry looked at Romney’s hand and declined the challenge. “I’m not in the betting business,” he said.

The moment was less dramatic than an October incident, when a perturbed Romney put his hand on Perry’s shoulder during a tense debate moment.